The Takeaway: Red Sox defense continues to cost Boston runs

BOSTON — Anyone who has watched the Red Sox this season has probably reached the same conclusion.

By Tim Britton

BOSTON — Anyone who has watched the Red Sox this season has probably reached the same conclusion.

This defense isn’t very good.

On the list of reasons why Boston lost 9-3 to the Yankees on Tuesday night, the defense ranks rather low. (For fun, it would rank behind things such as the following: Jon Lester was hit very hard; Jon Lester didn’t get any calls around the edges of the strike zone, which maybe says something about A.J. Pierzynski as a framer; Masahiro Tanaka was in cruise control aside from one four-pitch stretch.) But on the list of long-term concerns about the team, it might be at the very top.

The difficult thing about defense, though, has always been quantifying its impact. The stats aren’t as simple or accepted, and since most every defender is dealing with smaller sample sizes than a hitter, defensive statistics vacillate much more from year to year and challenge our preconceptions about a player’s skills.

But we’ll throw caution to the wind and try to measure how bad the Red Sox defense has been to this point.

The easiest way to look at it is just in terms of unearned runs. Boston allowed five of them on Tuesday night, and that matched the number the Sox allowed all last April. If Mike Napoli makes a play he said he needs to make in the top of the fifth, four Yankees runs don’t score in that frame.

But unearned runs are subject to the vagaries of a scorekeeper and MLB’s rather stringent definition of an error. And those who watched Tuesday can bear witness to the obvious flaws of that quantification. To wit, in the at-bat before Napoli dropped his liner, Brian Roberts hit a sinking line drive to right. Grady Sizemore broke late on the ball, and as he slid in to try to make the catch, the ball bounced out of his glove. It was ruled a hit, it loaded the bases in the inning, it placed more stress on Lester, who to his credit got a double-play grounder to get out of it without further damage.

Of course, that inning had started with Alfonso Soriano’s double off the wall. It wasn’t a play one would expect Jackie Bradley, Jr. to make, but it’s one Bradley could make. The same could be said for Brian McCann’s double to left-center that eluded Jonny Gomes in that inning.

So another way of examining the impact of poor defense is to look very broadly at a pitching staff’s batting average on balls in play. It’s the inverse of what we’re looking at with a hitter: A staff that yields a high BABIP is unlucky (or the victim of bad defense), and vice versa. For instance, a 2012 Tigers team that played Prince Fielder, Johnny Peralta and Miguel Cabrera on the infield allowed teams to hit .307 on balls in play. (And that’s despite a really good pitching staff.) That same year, the Rays held opponents to a .277 average on balls in play, well below the league average. Thirty points is a big difference.

The Red Sox entered Tuesday allowing a .318 BABIP, and that will only go up after 14 of the 30 balls the Yankees hit in their win went for hits. Not all of this is attributable to bad defense; you can’t expect the Sox outfielders to glove every ball hit hard off Lester on Tuesday. But we’re reaching a point where that’s more of a reasonable sample size, especially in relation to the roughly league average .294 the Red Sox allowed last season.

There are the more player-specific measures in defensive runs saved and ultimate zone rating, and the Red Sox rate out as a collective negative in both. Xander Bogaerts is already five runs below average at short. Sizemore is four runs below average in center, which is why Bradley is going to play there a lot almost regardless of how he performs offensively. Jonathan Herrera and Brock Holt have each been below average at third base filling in for Will Middlebrooks.

The imminent return of Middlebrooks, along with Gold Glover Shane Victorino in right, should help significantly. So will playing Bradley in center and Sizemore in left, where he could be an above-average fielder. But already the Red Sox have had to improvise a bit with their roster — as Daniel Nava will likely be able to attest to by Wednesday — to compensate for defensive shortcomings.

“We’ve given some extra outs. At this level, when you do that, you’re asking for trouble,” manager John Farrell said Tuesday night. “It’s something we continue to address, work at internally. There’s not going to be wholesale changes made. We have to go out and execute with greater efficiency.”